There is a market for almost every aspect of nature you can find in Alaska (or anywhere for that matter) if you just get creative. And the ability to earn money on nature hikes is limitless once you realize almost anything has a monetary value. Here are a few ideas!
Cottonwood Oil: An oil derived from cottonwood buds is one of the most expensive things Alaskans can sell. You can do research on making it and then sell it to herbal medicine suppliers or direct customers looking for it. It supplies arthritis relief and is believed to be one of the strongest natural remedies for chronic pain.
Alder Leaves: Alder leaves can be dried and sold as an additive to teas to help aid in headache relief. Some herbal suppliers may purchase them, but your best luck would be to sell them yourself.
Alder Cones: Dried alder cones can be sold as craft supplies for many crafters around the country. They're very popular in holiday crafts because they make such a unique small winter-time accent.
Willow Branches: Willow branches can be made into wicker and sold to craft stores and basket weavers. They can also be sold as chew toys for rabbits, gerbils, hamsters, chinchillas, and birds.
Blueberry Stems: Blueberry stems can be made into a tea! They add a sweet (lavenderish?) taste to other tea blends. They aren't often used alone, but can be sold as an additive. Many tea makers will buy them as well.
River Rocks: River rocks are purchased for a variety of things. Jewelry makers will buy certain colors or shapes for jewelry (quartz is popular). Religious/Spiritual suppliers will buy certain stones for ritual purposes. They can also be sold as home decor (vase accents, fountain addition, aquarium rocks).
Spruce/Hemlock Branches: Some wreath makers will buy spruce branches for wreaths. They're relatively stiff- which makes them a good decision for outdoor decorations. They also really like hemlock, because hemlock branches have a sort of 'droopy' evergreen appearance that can make beautiful holiday decor.
Dried Wildflowers: Many collectors will buy Alaskan dried wildflowers- specifically ones that are native to the arctic/subarctic and not other areas. Crafters will also sometimes buy them- but your best bet would be collectors and museums.
Tundra Lichen: Tundra lichen is bought by beauty suppliers to be used in making lotions, hair products, facial scrubs, and even soaps. It has a moisturizing property that is thought to help prevent wrinkles and promote glowing skin.
Moose Poop: These have been creatively formed into all sorts of things. Many artists buy them to make key chains, jewelry, novelty items, and other awesome things. But some pet stores will also buy them for Hermit Crab food.